This invention relates to the field of pressure sensitive adhesive labels.
In the conventional manufacture of pressure sensitive adhesive labels, a solution of a pressure sensitive material is applied to a substrate, or face stock, usually paper, in the form of a continuous web and dried. Thereafter a release sheet, usually provided as a continuous paper web coated with a release agent, is applied to the exposed pressure sensitive adhesive surface to form a substrate-pressure sensitive adhesive-release sheet label stock which is then wound on a rewind roll for further processing such as sheeting, slitting or other converting. After that, the label stock is typically printed, cut and collated by a printer to form individual printed sheets. Such sheets may be utilized for any number of uses including name tags, stickers, labels, etc., by simply peeling away the release paper and pressing the adhesive-coated side of the face sheet to the desired surface.
U.S. Pat. No. 4,377,616, the contents of which are incorporated by reference herein, discloses an opaque biaxially oriented polymer film structure comprising a thermoplastic polymer matrix core layer possessing numerous voids, a substantial number of which contain at least one spherical void-initiating particle, and transparent skin layers adhering to the surfaces of the core layer. The unique structure of the core layer imparts a much higher degree of opacity, possibly due to the effects of light scattering, than that possible by the use of opacifying pigment alone.
There is no suggestion, however, in U.S. Pat. No. 4,377,616 of incorporating the film structure disclosed therein in a pressure sensitive label stock.